1. Field of the Invention
The present invention relates to a fastening structure for fastening a shaft and a mounting structure for mounting a roller unit having a shaft to a fixed body such as a conveyor frame, which is fixed to the floor or the ground.
2. Description of Related Art
Some conventional type of roller conveyor has a plurality of motorized rollers arranged on a frame. Each of the motorized rollers is constructed by accommodating a motor and a reducer in a roller body supported rotatably relative to a shaft that is fastened to a fixed body such as the frame.
Conventional fasteners, including a shaft fastener disclosed in Japanese Laid-open Patent Application No. Hei. 11-268815 and a mounting plate 52 shown in FIG. 10 of the drawings attached hereto, have been used in order to fasten shafts of motorized rollers to fixed bodies such as frames. A shaft 51 of a conventional motorized roller 50 is fastened to a frame 53 (a fixed body) of a conveyor through a mounting plate 52, as shown in FIG. 10. Each end of the motorized roller 50 has a shaft 51 protruding therefrom. The outer surface of the shaft 51 is threaded. The plate 52 has a throughhole 54 at substantially its center. The shaft 51 is able to be fitted into the hole 54. The plate has four throughholes 55 at the four corners. The holes are used in mounting the plate 52 to the frame 53. The frame 53 has throughholes 56 into which the shaft 51 of the motorized roller 50 can be inserted and four threaded holes (not shown) around the throughhole 56.
The plate 52 is mounted to the frame 53 through screws 57, aligning the hole 54 with the hole 56 and aligning the holes 55 with the threaded holes respectively. The shaft 51 is inserted into the hole 56 of the frame 53 and into the hole 54 of the plate 52. The shaft 51 is fastened to the frame by tightening a nut 58. The shaft 51 cannot rotate relative to the frame 52 because the hole 54 of the plate 52 is in conformity with the shaft 51.
The above-described conventional mounting of the shaft 51 involves mounting of the plate 52 to the frame 53 via screws 57 so as to prevent rotation of the shaft 51. For mounting and fastening the shaft 51 to the frame, a throughhole 56 to accommodate the shaft 51 should be drilled on the frame 53 and threaded holes, not shown, in which the screws are driven, should be formed around the hole 56 on the frame 53. Thus the mounting and fastening of the shaft 51 takes a lot of time and effort and is inefficient. If the frame 53 is of complex shape, such as channel-shape or square U-shape in section shown in FIG. 10, the mounting and fastening becomes more troublesome. Thus the conventional fastening structure in which the plate 52 is preliminarily screwed on the frame 53 makes a rigid limitation on the shape of the frame 53, which is the fixed body.
Therefore, it is an object of the invention to provide a fastening structure of a shaft and a mounting structure of a roller unit having simple construction that is capable of fastening the shaft to any shape of fixed body easily and quickly. Other objects, advantages, features, and uses will become more apparent as the description proceeds, when considered with the accompanying drawings.
In one aspect of the invention to solve the above-described problem, a fastening structure including a fixed body and a shaft for fastening the shaft to the fixed body further includes a plate mountable on the shaft unrotatably relative to the shaft and having projections engageable with a surface of the fixed body and a fastener mountable on the shaft so as to urge the projections against the surface to prevent rotation of the plate relative to the fixed body about the axis of the shaft.
In this specification, a projection may be in any shape if it can prevent the rotation. It may be a tooth, a fluke, a pin, or a nail.
As the plate of the fastening structure has projections that engage with or bite into the surface of the fixed body, the plate need not be screwed so as to prevent rotation. Therefore, only one throughhole, through which the shaft extends, should be formed on the fixed body to fasten one shaft, without the need of forming throughholes in which the screws are driven. Therefore, easy and rapid fastening of a shaft to a fixed body is achieved.
As the plate is mounted on the shaft unrotatably relative to the shaft and is not rotatable relative to the fixed body about the axis of the shaft either, the shaft is fastened to the fixed body unrotatably relative to the body.
In another aspect of the invention, a fastening structure including a fixed body and a shaft for fastening the shaft to the fixed body further includes a plate mountable on the shaft unrotatably relative to the shaft and having projections engageable with a surface of the fixed body and a fastener mountable on the shaft so as to urge the projections against the surface to prevent rotation of the plate relative to the fixed body about the axis of the shaft, wherein the shaft includes an engaging portion and a supporting portion that is larger than the engaging portion in diameter, wherein the plate has a throughhole into which the engaging portion is fittable so as to prevent rotation of the plate relative to the shaft, and wherein the fixed body and the plate are sandwiched between the supporting portion and the fastener.
In the fastening structure, as the plate has projections engageable with a surface of the fixed body, the plate does not need to be screwed to prevent its rotation. Fastening work of the shaft is simplified and working efficiency is enhanced as threaded holes on the fixed body, which were necessary in conventional fastening structure, are not to be formed.
As the plate is mounted on the shaft unrotatably relative to the shaft and is not rotatable relative to the fixed body about the axis of the shaft either, the shaft is fastened to the fixed body unrotatably relative to each other.
In this specification, xe2x80x9ca supporting portion that is larger than the engaging portion in diameterxe2x80x9d means that the circumcircle of the supporting portion is larger in diameter than the circumcircle of the engaging portion. The section of the supporting portion may be of any shape such as rectangular and polygonal shape.
In still another aspect of the invention, a mounting structure including a roller unit, a shaft, a plate, a fixed body, and a fastener for mounting the roller unit to the fixed body, wherein the plate is mountable on the shaft unrotatably relative to the shaft and having projections engageable with a surface of a fixed body, wherein the roller unit has a roller body mounted on the shaft rotatably relative to the shaft and driven by a motor housed in the roller body, wherein the fastener is mounted on the shaft so as to urge the projections against the surface to prevent rotation of the plate relative to the fixed body about the axis of the shaft.
In the mounting structure of a roller unit, the plate does not need to be screwed to prevent its rotation, as the plate has projections engageable with a surface of the fixed body. As threaded holes on the fixed body, which were necessary in conventional fastening structure, are not to be formed, only one throughhole should be formed on the body to fasten one shaft. Thus the shaft of a roller unit can be fastened to the fixed body easily and rapidly.
As the plate is mounted on the shaft of the roller unit unrotatably relative to the shaft and is not rotatable relative to the fixed body about the axis of the shaft either, the shaft of the roller unit is fastened to the fixed body unrotatably relative to the body.
In the fastening structure or the mounting structure, the plate has a throughhole, the shaft includes an engaging portion and a supporting portion that is larger than the engaging portion in diameter, and the engaging portion is fittable into the throughhole so as to prevent rotation of the plate relative to the shaft.
As stated above, xe2x80x9ca supporting portion that is larger than the engaging portion in diameterxe2x80x9d means that the circumcircle of the supporting portion is larger in diameter than the circumcircle of the engaging portion. The section of the supporting portion may be of any shape such as rectangular and polygonal shape.
In the fastening structure or the mounting structure, the plate may be sandwiched between the fastener and the fixed body.
By the arrangement, as the plate is unrotatable relative to the fixed body and is mounted on the shaft unrotatably relative to the shaft either, the shaft is fastened to the fixed body unrotatably relative to the body.
If the shaft includes an engaging portion and a supporting portion that is larger than the engaging portion in diameter, the plate may be sandwiched between the supporting portion and the fixed body.
By the arrangement, as the projections engage with the surface of the fixed body, the plate is unrotatable relative to the fixed body. As the plate is mounted on the shaft unrotatably relative to the shaft either, the shaft is fastened to the fixed body unrotatably relative to the body.
By the arrangement also, rotational and vibrational forces acting on the shaft is transmitted to the fixed body and dissipated into the fixed body. Thus rotation of the plate relative to the fixed body is firmly prevented.
In the fastening structure or the mounting structure, preferably the plate is substantially rectangular with the projections at its four corners and with a throughhole at substantially its center. More preferably, each corner has the same number of projection or projections. Each corner may have one projection.
By the arrangement, rotational force acting on the plate about the axis of the shaft is distibuted to all the projections substantially evenly, firmly preventing rotation of the plate relative to the fixed body.
In the fastening structure or the mounting structure, preferably each of the projections has a sharp tip. In other words, each of the projections is preferably in the form of a tooth, a fluke, a pin or a nail.
By the arrangement, the projections engage with or bite into the fixed body firmly. Thus the plate is fastened to the fixed body firmly.
In the fastening structure or the mounting structure, the plate may have a throughhole into which the shaft is fittable, the plate may further have tabs around the throughhole, and each of the tabs may be deformable into a form in conformity with the shaft as the fastener is mounted on the shaft.
By the arrangement, rotation of the shaft relative to the plate is firmly prevented as each of the tabs deforms into a form in conformity with the shaft as the fastener is mounted on the shaft.
In the fastening structure or the mounting structure, the plate may have a noncircular throughhole, the shaft may have a portion that is noncircular in section and capable of being inscribed in the throughhole, the portion may extend over at least partial length of the shaft, and the portion may be fittable into the throughhole. The throughhole of the plate is noncircular as seen from the direction normal to the surface of the plate.
The sectional shape of the portion is not necessary identical with the shape of the hole. It is all right if the shapes prevent rotation of the shaft relative to the plate.
Even if the shaft in the structure receives a rotational force about the axis of the shaft, the shaft cannot rotate because it contacts the through-hole of the plate.